Abraham Lincoln’s Opposition to the Mexican War

Abraham Lincoln

As a congressman, Abraham Lincoln was very unpopular. The main reason for this is that he strongly opposed the Mexican War, a popular conflict.

Abraham Lincoln ran for a seat in the U.S. House of Representatives in 1846. He promised that he would only serve a single term. He was easily able to fulfill this promise, for he became extremely unpopular with Illinois voters. The main reason for this is that he openly opposed U.S. intervention into the Mexican War (1846-48). This opposition also made Lincoln a thorn in the side of then-President James K. Polk.

James K. Polk: The Manifest Destiny President

America’s eleventh president, James K. Polk, was elected in 1844. Like Illinois congressman Lincoln, Polk vowed only to serve one term in office. That, however, is where the similarities ended. Unlike Lincoln, President Polk supported going to war with Mexico. One of the spoils of this 22-month conflict was the American acquisition of land that eventually became the states of California, Nevada, and Utah. The U.S. also acquired portions of what would later become Colorado, Arizona, New Mexico, and Wyoming. This land acquisition through war became known as Manifest Destiny. The U.S. became swept up in it, the president was very popular, and generals Winfield Scott and Zachary Taylor– who became the twelfth president of the United States in 1848– became celebrated war heroes.

The Voice of Dissent

Congressman Lincoln and some of his fellow Whigs had a very different opinion of the president, Manifest Destiny, and the war. (Polk was a Democrat.) Lincoln believed that Polk had started the war based on a lie. On two notable occasions, Lincoln questioned Polk regarding his motives for going to war. Lincoln once took the House floor and asked Polk to prove that the Mexicans had crossed national borders in order to draw first blood on U.S. soil. This is what Polk claimed was the reason for the Mexican War. Upon addressing the president, Lincoln said: “Let the President [Polk] answer the interrogatories I proposed… Let him answer fully, fairly, candidly. Let him answer with facts, and not with arguments. Let him remember, he sits where Washington sat; and so remembering, let him answer as Washington would answer… so let him attempt no evasion, no equivocation.”

The President’s Opinion of the Illinois Congressman

As for President Polk’s opinion of the seemingly insignificant Lincoln, the commander-in-chief did not think too highly of the Illinois congressman. To make matters worse, the newspapers of the day did not think much of Lincoln, either. Worst of all was the fact that Lincoln’s constituents, including law partner, close friend, and fellow Whig William Herndon, believed that Lincoln’s vociferous opposition to the war was unpatriotic. According to Herndon, the future sixteenth president’s stance “sealed Lincoln’s doom as a Congressman.”


  1. Various Authors. “Illinois Lawyer: A Voice of Dissent Against a Popular Conflict– Mexican War, 1846-48,” excerpted from Abraham Lincoln: An Illustrated History of His Life and Times, p. 54 & 55. New York: TIME Books, Time Inc., 2009.